System and method for stator construction of an electric motor

Abstract

A system and method to reduce core loss in the stator of an electric motor by first preparing laminations of the stator and/or rotor in a water jetting operation, punching or stamping operation, laser cutting operation, or similar manufacturing operation, and then subjecting the laminations to a temperature treatment in a manner such that, upon assembly into a stator and/or rotor of an electric motor and operated within expected parameters, core loss is reduced. The system and method subjects the laminations to a cold bath preferably consisting of liquid nitrogen, after stamping but preferably prior to assembly, and then stacking the laminations together for assembly as a stator and/or rotor of an electric motor.

What is claimed is: 
     
       1. A method to reduce core loss in an electric motor by preparing laminates of at least one of the stator and rotor such that, upon assembly into a stator and rotor of an electric motor and operated within expected parameters, core loss is reduced, comprising:
 forming at least one of a stator and a rotor laminate; 
 subjecting the at least one stator and rotor laminate to a reduced temperature bath; and 
 assembling a plurality of the stator and rotor laminates into a stator and rotor of an electric motor, respectively, such that upon operation, the electric motor exhibits reduced core loss, 
 wherein the at least one stator and rotor laminate is subjected to the reduced temperature by submersion of the laminate into a cold bath, 
 wherein the at least one stator and rotor laminate remains submersed in the cold bath for a period of up to 8 hours and is then removed in a reverse process until completely free of the cold bath, and 
 wherein the at least one stator and rotor laminate is held free of the cold bath and allowed to substantially reach room temperature before assembly. 
 
     
     
       2. The method of  claim 1 , wherein the at least one stator and rotor laminate is formed using one or more of a water jetting operation, punching operation, stamping operation and laser cutting operation. 
     
     
       3. The method of  claim 1 ,
 wherein the cold bath is comprised of a liquid nitrogen bath comprising an insulated chamber containing liquid nitrogen, and 
 wherein the liquid nitrogen is introduced to the cold bath at a rate of up to 7 gallons per hour. 
 
     
     
       4. The method of  claim 1 , wherein the temperature of the cold bath is maintained between 63 K and 77.2 K (−346 F and −320 F) at normal atmospheric pressure. 
     
     
       5. The method of  claim 1 , wherein the at least one stator and rotor laminate is at a room temperature of between 293 K and 298 K (68 F and 77 F) before being placed into the cold bath. 
     
     
       6. The method of  claim 1 ,
 wherein the stator comprises a plurality of stator laminates stacked together and the rotor comprises a plurality of rotor laminates stacked together, 
 wherein at assembly, the plurality of laminates are arranged with a thick edge of each laminate aligned with a thin edge of a laminate below it, and 
 wherein a stacking pressure of about 250 pounds per square inch is applied to the arranged laminates. 
 
     
     
       7. The method of  claim 1 ,
 wherein at assembly, the stator and rotor is shortened by one laminate at each end of the stator and the rotor, and 
 wherein the stator and the rotor each has a stacking factor of at least 98 percent. 
 
     
     
       8. The method of  claim 1 , wherein at assembly, a wire winding having a varnish vacuum pressure impregnation is applied to the stator and rotor. 
     
     
       9. The method of  claim 1 , wherein the assembly of at least one of the stator and rotor is performed before subjecting the laminates to the reduced temperature bath. 
     
     
       10. A method to reduce core loss in laminates of an electric motor, comprising:
 forming at least one of a stator or a rotor laminate; 
 subjecting the laminate at a room temperature of between 293 K and 298 K (68 F and 77 F), to a reduced temperature bath maintained between 63 K and 77.2 K (−346 F and −320 F) at normal atmospheric pressure; and 
 assembling a plurality of laminates into an electric motor such that upon operation, the electric motor exhibits reduced core loss. 
 
     
     
       11. The method of  claim 10 ,
 wherein the reduced temperature bath is comprised of a liquid nitrogen bath, and 
 wherein the liquid nitrogen bath comprises an insulated box containing liquid nitrogen and the liquid nitrogen is introduced to the bath at a rate of up to 7 gallons per hour. 
 
     
     
       12. The method of  claim 10 , wherein the laminate is placed into the reduced temperature bath for a period of up to 8 hours. 
     
     
       13. The method of  claim 10 , wherein the assembly of laminates is performed before subjecting the laminates to the reduced temperature bath. 
     
     
       14. A method to reduce core loss in laminates of an electric motor, comprising:
 subjecting at least one of a stator or a rotor laminate at a room temperature of between 293 K and 298 K (68 F and 77 F), to a reduced temperature bath maintained between 63 K and 77.2 K (−346 F and −320 F) at normal atmospheric pressure; and 
 assembling a plurality of laminates at a room temperature of between 293 K and 298 K (68 F and 77 F) into an electric motor such that upon operation, the electric motor exhibits reduced core loss. 
 
     
     
       15. The method of  claim 14 ,
 wherein the reduced temperature bath is comprised of a liquid nitrogen bath, and 
 wherein the liquid nitrogen bath comprises an insulated box containing liquid nitrogen and the liquid nitrogen is introduced to the bath at a rate of up to 7 gallons per hour. 
 
     
     
       16. The method of  claim 14 , wherein the laminate is placed into the reduced temperature bath for a period of up to 8 hours. 
     
     
       17. The method of  claim 14 , wherein the assembly of laminates is performed before subjecting the laminates to the reduced temperature bath.